Update Xen header files

Update Xen header files

The original patch from Owen contained too much whitespace damage. This
patch replaces it with the results of an invocation of get_xen_headers.py
and includes all resulting header updates.

NOTE: This patch adds one extra header (physdev.h) and a fix to remove
      now-duplicate definitions of DOMID_INVALID from frontend.c.

Suggested-by: Owen Smith <owen.smith@citrix.com>
Signed-off-by: Paul Durrant <paul.durrant@citrix.com>